Applicants"" invention relates to a data storage management system, apparatus, and method to permit a computer system to record information in alternative information storage architectures using a data storage device having a fixed device architecture. Applicants"" invention further relates to a data storage management system and method to increase the storage capacity utilization of data storage media.
An explosion of computer data and information requires an ever increasing amount of computer readable storage space. Increasing data storage capacity requires improved storage management systems to backup and protect data sets, and migrate less active data sets to secondary storage to increase primary storage space. A data set consists of any collection or grouping of data. In certain systems, a data set may include control information used by the system to manage the data. The terms data set and file are generally equivalent and sometimes are used interchangeably. Hierarchical storage management (HSM) programs manage storage devices, such as tape libraries, to control the flow of data between primary and secondary storage facilities.
In a hierarchical storage management system, data is stored in different types of storage devices depending upon the frequency of usage of the data. For instance, a system may include multiple storage media types to store data having different usage patterns and likelihoods of access. More frequently used data may be stored on direct access storage devices (DASD) comprising high-performance rapid access storage devices, such as hard disk drives. Such readily accessible data is sometimes referred to as level zero volumes. Less frequently used data may be archived on slower and less expensive, demountable storage media, such as optical disks, magnetic tape cartridges, etc. Such archive volumes are often referred to as level two storage.
Two common functions initiated by host systems in hierarchical storage management systems include migration and recall. Migration involves the movement of data from level 0 to level 1 or to level 2 storage to make more room for more frequently accessed data on the primary level 0 storage devices. If a host system attempts to access a data set that has been migrated to level 1 or level 2 storage, then the recall function would be initiated to move the requested data sets to level 0.
International Business Machines Corporation (IBM(copyright)) provides the Data Facilities Storage Management Subsystem (DFSMS(copyright)) software which is included in the IBM MVS/ESA(trademark), OS/390(copyright), and z/OS(copyright) operating systems. This software allows host systems to perform hierarchical storage management operations, such as migration and recall. DFSMS and OS/390 are registered trademarks of IBM, and MVS/ESA is a trademark of IBM. The operation and implementation of the DFSMS system are described in IBM publications xe2x80x9cDFSMS/MVS VIR3 General Information,xe2x80x9d IBM document no. GC26-4900-04 (IBM Copyright, 1980, 1995) and xe2x80x9cDFSMS/MVS VIR3 DFSMShsm Storage Administration Guide,xe2x80x9d IBM document no. SH21-1076-02 (IBM Copyright 1984, 1995), which publications are incorporated herein by reference in their entirety.
Certain prior art HSM programs, tape operating systems, and data storage devices utilize a 22-bit block id format. Using a block size of 16 kilobytes, such a 22-bit blockid format can accommodate a maximum number of about 4,000,000 blocks. When this maximum number of blocks is encountered, the data storage subsystem returns a logical end-of-tape indication, and the volume, i.e. the tape, is regarded by the host computer as xe2x80x9cfilledxe2x80x9d regardless of the actual physical space still available. On the other hand, use of a 32 bit file block addressability mode allows storage of more than 4,000,000,000 blocks per volume, such as a magnetic tape.
What is needed is an data management system and method that supports the capability to switch between alternative blockid architectures, i.e. between a 22 bit blockid format and a 32 bit blockid format, and vice versa. Applicants"" invention includes a data management system comprising an HSM program, a data storage and retrieval system operating system, and data storage device microcode; apparatus including a data storage and retrieval system and a data storage device; and a method using Applicants"" data management system and apparatus, to implement the capability to switch between alternative information storage architectures, and thereby, to increase the capacity utilization of data storage media.
Applicant""s invention includes a method to increase the storage capacity of data storage media. Applicants"" method uses a data storage device comprising a fixed device architecture, where that data storage device is capable of operating in a first capacity mode or in a second capacity mode, and where that data storage device is capable of switching between the first capacity mode and the second capacity mode. In certain embodiments, the first capacity mode utilizes a 22 bit blockid format and the second capacity mode utilizes a 32 bit blockid format. In other embodiments, the first capacity mode utilizes a 32 bit blockid format and the second capacity mode utilizes a 22 bit blockid format.
Further according to Applicants"" method, the data storage device receives a request from a host computer to record designated information on a designated data storage media using a specified capacity mode. In response to that request, Applicants"" method switches the data storage device from its default capacity mode to the specified capacity mode, and then records the designated information on the designated data storage medium using that specified capacity mode.
Applicants"" invention further includes a computer code product comprising a data management system which includes hierarchical storage manager program, a data retrieval system operating system, and data storage device microcode, which supports the capability to switch between alternative information storage architectures, and thereby, increase the capacity utilization of data storage media.
Applicants"" invention further includes a data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein for implementing Applicants"" method to support the capability to switch between use of alternative information storage architectures, and thereby, to increase the capacity utilization of data storage media.